ASVAB Mechanical Comprehension Practice Test 611570 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.38
Score	0%	68%

Review

1 What is the mechanical advantage of this inclined plane if the length of the ramp is 14 ft. and the height of the green box is 7 ft.?

82% Answer Correctly

	4
	2
	5
	3.5

Solution

The mechanical advantage (MA) of an inclined plane is the effort distance divided by the resistance distance. In this case, the effort distance is the length of the ramp and the resistance distance is the height of the green box:

MA = \( \frac{d_e}{d_r} \) = \( \frac{14 ft.}{7 ft.} \) = 2

Which class of lever is used to increase force on an object in the same direction as the force is applied?

53% Answer Correctly

	first
	third
	second
	all of these

Solution

A second-class lever is used to increase force on an object in the same direction as the force is applied. This lever requires a smaller force to lift a larger load but the force must be applied over a greater distance. The fulcrum is placed at one end of the lever and mechanical advantage increases as the object being lifted is moved closer to the fulcrum or the length of the lever is increased. An example of a second-class lever is a wheelbarrow.

Which of the following is not a characteristic of a ceramic?

61% Answer Correctly

	high melting point
	chemically stable
	low corrosive action
	low density

Solution

Ceramics are mixtures of metallic and nonmetallic elements that withstand exteme thermal, chemical, and pressure environments. They have a high melting point, low corrosive action, and are chemically stable. Examples include rock, sand, clay, glass, brick, and porcelain.

4 What is the efficiency of a machine has work input of 220 ft⋅lb and work output of 176 ft⋅lb?

67% Answer Correctly

	80%
	0%
	1%
	40%

Solution

Due to friction, a machine will never be able to utilize 100% of its work input. A certain percentage of that input will be lost in overcoming friction within the machine. Effeciency is a measure of how much of a machine's work input can be turned into useful work output and is calculated by dividing work output by work input and multiplying the result by 100:
\( Efficiency = \frac{Work_{out}}{Work_{in}} \times 100 \) \( = \frac{176 ft⋅lb}{220 ft⋅lb} \times 100 \) \( = 80% \) %

5 If A = 6 ft. and the green box weighs 40 lbs. what is the torque acting on the A side of this lever?

75% Answer Correctly

	480 ft⋅lb
	240 ft⋅lb
	960 ft⋅lb
	120 ft⋅lb

Solution

For a lever, torque is weight x distance from the fulcrum which, in this case, is: 40 ft. x 6 lbs. = 240 ft⋅lb